Biscuit cutters, or plate joiners as they are sometimes referred to, are a relatively commonly used tool for forming alignment slots in boards to be glued together. A biscuit, formed typically of plywood, is used to align a pair of board edges precisely during a gluing operation. Biscuits are used in conjunction with biscuit cutters in applications where dowel pins have historically been used. Biscuits offer a number of significant advantages over dowel pins, the most important of which is ease of alignment when biscuits are used to align board edges in preparation of gluing.
When using a biscuit cutter, the distance from the top planar surface of the workpieces or boards to be joined must be precisely controlled in order to form a flush tabletop or a square 90.degree. corner. The transverse location of the biscuit is typically not critical as is the case with the multiple dowel pins. Therefore, it is very easy to install multiple biscuits along an elongated glued edge joint since there will typically be ample transverse clearance between the arcuate slot cut in the workpiece edge and the biscuit. The thickness of the slot relative to the biscuit width however, is slightly controlled to provide a very snug fit to precisely align the workpiece planar surfaces.
Typically, a user wanting to join two board edges together will align the boards in their intended final orientation and mark a series of pencil lines across the edge joint generally perpendicular to the edge. The boards are then separated and a biscuit cutter is used to cut slots in the board edges a predetermined distance from the planar surface generally aligned with the pencil centerline markings. This is relatively easy to do when the boards are long and the biscuits are located a substantial distance from the board ends.
However, when the boards to be joined are quite narrow or where it is necessary to locate biscuits immediately adjacent the board end, the user must be extremely careful so that the biscuit slot does not break out into the board end causing a cosmetic defect. When making a shallow drawer for example, the drawer may not be much deeper than the biscuit length. Therefore it is important to carefully center the biscuit so that the arcuate slots formed in the drawer rails and panels do not break out.
Moreover, the biscuit itself is not a good indication of slot length because the slot will always be longer than the biscuit. This is due to biscuit slot clearance and the fact that the biscuit is truncated so that its length is significantly less than the length of the elongated slot at the workpiece edge surface.